The present invention pertains generally to vascular occlusion catheters and methods of vascular pre-conditioning while controlling occlusion and perfusion during an occlusion procedure. Pre-conditioning is employed to mitigate ischemia before, during and/or after a vascular occlusion procedure, as well as used to reduce or ameliorate the onset of hypertension during or reduce or ameliorate the onset of hypotension after a vascular occlusion procedure. Vascular occlusions may be indicated in either the venous system and/or the arterial system. Endoarterial occlusion is a procedure in which a blood vessel is at least partially occluded in order to restrict blood flow upstream or downstream of the occlusion site for purposes of a vascular procedure or repair. It is known that transient hypertension is a risk factor in arterial occlusion, particularly aortic occlusion. Transient hypertension occurs when the blood pressure upstream of the occlusion site rises to a potentially unsafe level during the time duration of the occlusion. Upon completion of a procedure requiring arterial occlusion, particularly aortic occlusion, care must be taken during the process of reestablishing blood flow to reduce or ameliorate the onset of hypotension. Thus, arterial occlusion carries with it two twin risks, hypertension during the occlusion and hypotension as the occlusion is withdrawn and blood flow restored that must be managed.
In addition to hypotension and hypertension, techniques allowing partial flow of blood and related fluids past the occlusion member may be desirable to provide at least partial blood flow to portions of the patient's body downstream of the occlusion member. At least partial perfusion past the occlusion member can provide the benefits of focusing or directing a majority of blood flow to the brain, heart and lungs or other upstream portions of the patient, but also potentially increasing the amount of time the occlusion member can be implanted in the patient, by providing at least partial blood flow to the patient's organs downstream of the occlusion member, such as to the patient's liver, digestive tract, kidneys and legs.
Referring to Fig. A, partial perfusion may be accomplished by reducing the size of an occlusion member or occlusion balloon 1 that is attached to a catheter 2. The occlusion balloon 1 may, for example, be partially deflated to allow blood to flow between outer surfaces 1a of the occlusion balloon 1 and inner surfaces 3a of a vessel 3 within which the occlusion balloon 1 is positioned. This, for example, deflation of the occlusion balloon 1 may cause the occlusion balloon 1 to lose contact with the inner surface 3a of the vessel 3, thereby causing movement of the occlusion balloon 1 and partial vibration between the vessel 3 and the occlusion balloon 1 that is undesirable. Such loss of contact with the inner surfaces 3a of the vessel 3 by the occlusion balloon 1 is represented in Fig. A, by a cylindrical channel 4 defined between the outer surface 1a of the occlusion balloon 1 and the inner surfaces 3a of the vessel 3. Loss of contact with the inner surface 3a of the vessel 3 by the occlusion balloon 1 may also result in the occlusion balloon 1 and attached catheter 2 being urged downstream in the vessel 3, thereby moving the occlusion balloon 1 out of its preferred placement. It would be desirable to design, develop and implement an occlusion balloon catheter that maintains contact with the vessel during partial perfusion to reduce or eliminate such vibrations and movement of the occlusion member during partial perfusion.
Temporary aortic occlusion as an operative method to increase proximal or central perfusion to the heart and brain in the setting of shock due to major trauma is generally known. Despite potential advantages over thoracotomy with aortic clamping, resuscitative endovascular balloon occlusion of the aorta (“REBOA”) for trauma has not been widely adopted.
Many attempts have been made at developing technologies to control non-compressible abdominal hemorrhage. For example, non-occlusive, abdominal tamponade procedures have been developed to address the problem of non-compressible hemorrhage, such as introducing an expandable, biocompatible foam into the abdominal cavity to apply pressure to the abdominal organs and vasculature. Pharmacological efforts have also been developed to address the problem of non-compressible hemorrhage. Conventional REBOA procedures are typically performed in an operating room and with the aid of fluoroscopy or other imaging.
Devices that automate inflation and deflation of a balloon are generally known. Intra-aortic balloon counterpulsation catheters for blood pressure augmentation coordinated with electrocardiography signals are also known. Over-inflation safety devices are also known, such as a pressure-relief valve coupled to an inflation lumen that opens when pressure within the inflation lumen exceeds a threshold pressure, but relative pressure within the occlusion balloon is necessary to maintain occlusion of the blood vessel.
It would be desirable to design, develop and implement a system that intermittently and automatically releases an occlusion balloon or member by releasing apposition of the occlusion balloon or member against the vascular wall and allowing perfusion past the occlusion balloon or member in response to a physiological parameter, then re-establishing occlusion in response to potential changes in the physiological parameter, either during a vascular repair procedure to control hypertension or post-repair procedure to control hypotension. It would also be desirable to design, develop and implement a system that allows perfusion past the occlusion balloon or member while maintaining engagement between the occlusion balloon or member and the walls of the vasculature, preferably an artery and more preferably the aorta, to prevent vibration, movement, sliding or shifting of the occlusion balloon or member as blood flows past the occlusion balloon. In addition, it is desirable to design, develop and implement an occlusion balloon that permits relatively fine control of a pressure ratio between proximal and distal sides of the occlusion balloon and, therefore, relatively fine control of blood flow across the occlusion balloon through the vessel. The preferred embodiments of the present invention addresses certain of these limitations of the prior art occlusion systems.
In addition, it is desirable to design, develop and implement an occlusion balloon that permits relatively fine control of a pressure ratio between proximal and distal sides of the occlusion balloon and, therefore, relatively fine control of blood flow across the occlusion balloon through the vessel. Existing occlusion balloons are difficult to modulate pressure drop across the balloon. A relatively small change in balloon volume or internal pressure often results in drastic changes in blood pressure between proximal and distal sides of the occlusion balloon, resulting in full occlusion or a relatively high rate of volumetric blood flow across the balloon. It is desirable to design, develop and deploy an occlusion system that is less sensitive to slight pressure changes in the occlusion balloon and provides a more gradual change in blood flow past the occlusion balloon. The preferred present invention addresses these shortcomings of prior art occlusion balloons.